The Mooka Boys are at the end of their tether. Sam Mehan calls in some tech gurus to map out the treacherous parts of their underground mine with the help of “Spot” the robot dog. The Opal Whisperers return to Queensland to search for the ‘Yowah Nut’.

The Bushmen have grand plans to drill a new shaft to connect some old underground drives. Slim Pickings' entire operation is shut down when their 60-year-old tractor breaks down. The Cheals must head underground to reach their enormous $500k target.

The Mooka Boys make a discovery that could turn their fortunes around. The Cheals face constant machinery failures. After collapsing the decades old underground mine on their claim, The Opal Whisperers search for Yowah Nuts in the scorching heat.

Slim Pickings' Lee Hobden and Roger Williams look for clues to the whereabouts of buried treasure in the machinery discarded by the old-time miners. The Bushmen have decided to move to a promising new claim they've christened ‘Froggies’.

The Bushmen accidentally unleash a potentially fatal threat to the team. Slim Pickings consult a historian who helps them search for another source of old timers paydirt. Matt and Cozza reach out to former Mooka Boy Dale Groben to lift the team's spirits.

The Cheals are finally getting their second agitator up and running. The Blacklighters find impressive shell fossils in the face of their open cut mine. The Opal Whisperers are bringing in Kelly's partner Dan to help them break ground fast.

The Misfits return to their claim and find it's been soaked by torrential rain. The Opal Lovers dig an intimidatingly deep trench on their Digger's Gully claim. The Bushmen are down on their luck once again, with Jake absent from work with a broken jaw.

The Opal Whisperers are on a mission to unearth something worthwhile from their newly excavated 9-meter-deep trench. Aging machinery slows The Bushmen down. The Cheals are finally doubling the output from their Turner's Rush claim.

The Opal Lovers excavate old drives in search of red crystal opal. Mechanical problems are once again giving the Mooka Boys a headache. Slim Pickings strike a deal with a local mining family to process the waste dirt on their claim.

The Blacklighters are pushing for a big pay day. With weather threatening their operation, the Misfits have to get crafty with their setup. The Opal Whisperers are feeling the pressure after Isaac is invited to be a star guest of the London Gem Show.

The Blacklighters have just one week left to strike opal before the blistering summer heat shuts them down. The Bushmen scramble to beat mechanical failures and rising temperatures. The Mooka Boys are reunited with their chief mechanic Leif Tanzer.